JP2017161032A - Telescopic shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a structure which can make a male shaft and a female shaft stably slide even if there is employed the structure which can suppress the wobbling of an engagement part of a male spline part of the male shaft and a female spline part of the female shaft in a rotation direction to the minimum.SOLUTION: A coating layer 59 is formed in a portion toward a one-end shifted portion of a small-diameter shaft part 33 in an axial direction from one end edge in the axial direction via a male spline part 38 out of an external peripheral face of an inner shaft 9a. Then, by forming a slit 35 whose one end in the axial direction is opened at one end face of the inner shaft 9a in the axial direction, and a cross section shape is formed into a cross shape, and which is opened at four-point positions of an external peripheral face of a spline forming part 31, and covering it with the coating layer 59, a portion toward one end part of the inner shaft 9a in the axial direction from an intermediate part in the axial direction is divided into four pieces in the circumferential direction.SELECTED DRAWING: Figure 3

Description

  The telescopic shaft according to the present invention is used as, for example, an intermediate shaft that constitutes an automobile steering device.

  2. Description of the Related Art Conventionally, an automobile steering apparatus having a structure as shown in FIG. 1 is known. In this steering apparatus, a steering wheel 1 is fixed to a rear end portion of a steering shaft 2. At the same time, the front end portion of the steering shaft 2 is connected to the base end portion of the input shaft 6 constituting the steering gear unit 5 via a pair of universal joints 3 a and 3 b and the intermediate shaft 4. Further, a pair of left and right tie rods 7 and 7 are pushed and pulled by a rack and pinion mechanism built in the steering gear unit 5 so that the steering angle corresponding to the operation amount of the steering wheel 1 is given to the pair of left and right steering wheels. It is configured to grant.

  The intermediate shaft 4 incorporated in such a steering device is, for example, for preventing (absorbing) vibrations input from an automobile during traveling from being transmitted to the steering wheel 1 or, A telescopic type is used in order to incorporate it into the car body with its full length shortened.

  FIG. 2 shows the structure of the telescopic intermediate shaft 4 described in Patent Document 1. The intermediate shaft 4 includes an inner shaft 9 having a male spline portion 8 formed on the outer peripheral surface of one axial end portion (the front end portion and the left end portion in FIG. 2; the end portion on the outer tube 10 side in the assembled state). And a circular outer tube 10 having a male spline portion 8 and a female spline portion 12 that can be spline-engaged with each other. Then, by engaging the male spline portion 8 and the female spline portion 12 by spline engagement, the inner shaft 9 and the outer tube 10 are combined in a state where the torque can be transmitted and the entire length can be expanded and contracted. .

In the case of the structure shown in FIG. 2, the inner shaft 9 is disposed on the rear side (the front-rear direction refers to the front-rear direction of the vehicle body; the same applies throughout the present specification and claims), and The outer tube 10 is arranged on the front side. The first yoke 11 constituting the universal joint 3a disposed on the rear side of the universal joints 3a and 3b is externally fitted (fixed) to the other axial end of the inner shaft 9. ing. On the other hand, a second yoke 13 constituting the universal joint 3b disposed on the front side of the universal joints 3a and 3b is externally fitted and fixed (press-fitted) to one axial end portion of the outer tube 10. .
The coupling between the inner shaft 9 and the first yoke 11 or the coupling between the outer tube 10 and the second yoke 13 can be performed by welding. Further, a structure in which the inner shaft is disposed on the front side and the outer tube is disposed on the rear side can be employed as in the structure of the embodiment described later.

  Like the intermediate shaft 4 having the above-described configuration, the telescopic shaft in which the inner shaft 9 and the outer tube 10 can transmit torque and can be expanded and contracted (slidable) in the axial direction has a rotational direction. It is required that the rattling is small and the sliding resistance during expansion and contraction is small. Therefore, conventionally, a coating layer made of a synthetic resin having a low friction coefficient such as polyamide resin is provided on the outer peripheral surface of the male spline portion 8 of the inner shaft 9, and the male spline portion 8 and the female spline portion 12 are provided. Are engaged with each other with a tightening margin. However, in the case of such a structure, if the rigidity in the radial direction of the inner shaft 9 where the coating layer is provided is high, the variation in sliding resistance (sliding load) with respect to the tightening margin becomes sensitive. Therefore, it may be difficult to stabilize the sliding of the inner shaft 9 with respect to the outer tube 10. Such a problem becomes more prominent as the tightening margin is increased in order to sufficiently suppress the rattling.

JP 2015-21596 A

  In view of the circumstances as described above, the present invention adopts a structure that can suppress the rattling in the rotational direction of the engaging portion between the male spline portion of the male shaft and the female spline portion of the female shaft, A structure of a telescopic shaft capable of stably sliding the male shaft and the female shaft is realized.

The telescopic shaft of the present invention includes a male shaft, a coating layer, and a female shaft.
Among these male shafts, a male spline portion is formed on the outer peripheral surface of one axial end portion.
The said coating layer is provided in the state which covers the outer peripheral surface of the said male spline part.
The female shaft has a female spline portion formed on the inner peripheral surface.
Then, by engaging the male spline part and the female spline part through the coating layer, the male shaft and the female shaft can transmit torque and extend and contract their entire length. It is combined.
In particular, in the telescopic shaft of the present invention, the male shaft has an outer peripheral surface at one axial end portion of the male shaft and a cross-shaped slit opened at one axial end surface of the male shaft. The slit is covered with a coating layer.

  In the case of the telescopic shaft of the present invention having the above-described configuration, the coating layer is provided so as to cover the outer peripheral surface of the male spline portion of the male shaft. Along with this, an outer peripheral surface of one end of the male shaft in the axial direction and a slit opened in one end surface of the male shaft in the axial direction are formed on the male shaft. For this reason, the radial rigidity of at least the portion where the slit is formed among the portions where the male spline portion of the male shaft is formed can be appropriately reduced. Therefore, in order to prevent rattling in the rotational direction of the engaging portion between the male spline portion of the male shaft and the female spline portion of the female shaft, this tightening portion can be tightened even if it has a tightening allowance. Variation in sliding resistance (sliding load) with respect to the margin can be made insensitive, and sliding of the male shaft with respect to the female shaft can be stabilized.

The partially cut side view which shows an example of the steering apparatus known conventionally. The partial cutting side view which takes out and shows an intermediate shaft. The partial cutaway side view which shows the intermediate shaft which attached the 10 axis | shaft type universal joint to the both ends which shows embodiment of this invention. Similarly, the perspective view which shows an axial direction one end part from the axial direction intermediate part of the inner shaft in the state where the synthetic resin intervened inside the slit. Similarly, the side view (a) which shows an axial direction one end part from the axial direction intermediate part of an inner shaft, and AA sectional drawing (b) of (a).

[Embodiment]
An example of an embodiment of the present invention will be described with reference to FIGS. In this example, the present invention is applied to an intermediate shaft constituting a steering device. However, the present invention can be applied to a structure of a telescopic shaft used for various purposes other than such an intermediate shaft. Further, the structure of the steering apparatus incorporating the intermediate shaft 4a of this example has the same structure as the steering apparatus shown in FIG. However, the intermediate shaft 4a of this example is not limited to the structure of the steering apparatus shown in FIG. 1, but can be incorporated in various conventionally known steering apparatuses. Hereinafter, after briefly explaining the structure of the steering device, the structure of the intermediate shaft 4a of this example will be described.

  In the steering apparatus incorporating the intermediate shaft 4a of this example, the steering wheel 1 (see FIG. 1) is fixed to the rear end portion of the steering shaft 2. At the same time, the front end portion of the steering shaft 2 is connected to the base end portion of the input shaft 6 constituting the steering gear unit 5 through a pair of universal joints 3c and 3d and the intermediate shaft 4a. . Furthermore, the rack and pinion mechanism built in the steering gear unit 5 pushes and pulls the pair of left and right tie rods 7 and 7 so that the steering angle corresponding to the operation amount of the steering wheel 1 is given to the pair of left and right steering wheels. It is configured to grant.

  The intermediate shaft 4a has one axial end portion of the inner shaft 9a corresponding to one example of the male shaft described in the claims (the right end portion in FIG. 3 and the outer tube 10a side in the assembled state). And the other axial end portion of the outer tube 10a corresponding to one example of the female shaft (the left end portion in FIG. 3 and the end portion on the inner shaft 9a side in the assembled state). Are combined so that torque can be transmitted and the entire length can be expanded and contracted. In the case of this example, the inner shaft 9a is disposed on the front side, and the outer tube 10a is disposed on the rear side. Hereinafter, a specific structure of the intermediate shaft 4a will be described.

The outer tube 10 a includes a small-diameter cylindrical portion 18, a continuous portion 19, a large-diameter cylindrical portion 20, and a yoke portion 21 in order from the other axial side.
Of these, the small-diameter cylindrical portion 18 has a cylindrical shape, and is provided in a portion of the outer tube 10a extending from the other axial end portion to the axial intermediate portion. The outer peripheral surface of such a small diameter cylindrical portion 18 has a cylindrical surface shape whose outer diameter dimension does not change over the entire length in the axial direction. Further, on the inner peripheral surface of the small-diameter cylindrical portion 18, a female spline portion 22 composed of a plurality of concave portions and convex portions that are long in the axial direction and are alternately formed in the circumferential direction is formed over the entire length. Yes.

The continuous portion 19 has a partial conical cylindrical shape in which the outer diameter dimension and the inner diameter dimension increase toward the one side in the axial direction (the right side in FIG. 3), and the other end in the axial direction is the axial direction of the small diameter cylindrical part 18. It is continuous to one edge.
The large-diameter cylindrical portion 20 has a cylindrical shape, and the other axial end edge is continuous with the one axial end edge of the continuous portion 19. The inner diameter and outer diameter of such a large diameter cylindrical portion 20 are larger than the inner diameter and outer diameter of the small diameter cylindrical portion 18.

  The yoke portion 21 constitutes the universal joint 3c, and is pivoted from two axial positions on one end edge in the axial direction of the large-diameter cylindrical portion 20 on the opposite side in the diametrical direction. It consists of a pair of arm parts 23 and 23 provided in a state extending in one direction. A pair of circular holes 24, 24 are formed in the vicinity of one end in the axial direction of both the arm portions 23, 23 in such a manner that the central axes are coaxial. In the assembled state shown in FIG. 3, bottomed cylindrical bearing cups 25 and 25 are fitted and fixed inside the circular holes 24 and 24, respectively. At the same time, a pair of shaft portions 28 of the four shaft portions 28, 28 constituting the cross shaft 27 are disposed inside the bearing cups 25, 25 via a plurality of needles 26, 26, respectively. The end part of 28 is supported rotatably.

Of the four shaft portions 28, 28 constituting the cross shaft 27, a pair of shaft portions 28 other than the shaft portions 28, 28 supported in the circular holes 24, 24 of the yoke portion 21 ( The ends of one shaft portion 28 are not shown) and are formed on a pair of arm portions 30 (one arm portion 30 is not shown) constituting a yoke 29 supported and fixed to the front end portion of the steering shaft 2. A circular hole (not shown) is rotatably supported via a bearing cup and a needle (not shown).
In the case of this example, the structure in which the yoke portion 21 is provided integrally with the outer tube 10a is adopted. However, the outer tube and the yoke portion are provided separately and are joined and fixed by welding or fitting. Can also be adopted.

  The inner shaft 9 a includes a spline forming portion 31, a continuous portion 32, a small diameter shaft portion 33, a yoke portion 34, and a slit 35 in order from one axial side (the right side in FIG. 3).

  Among these, the spline formation part 31 is provided in the part from the axial direction intermediate part of the said inner shaft 9a to an axial direction one end part. On the outer peripheral surface of the spline forming portion 31, a male spline portion 38 composed of a plurality of concave portions 36 and 36 and convex portions 37 and 37 that are long in the axial direction and are alternately formed with respect to the circumferential direction. Is formed.

  The continuous portion 32 is formed in a portion of the inner shaft 9a adjacent to the other axial side of the spline forming portion 31. On the outer peripheral surface of such a continuous portion 32, a plurality of concave portions 39, 39 alternately formed in the circumferential direction and a cross-sectional shape with respect to a virtual plane including the central axis of the inner shaft 9a have a right triangle shape. The incomplete spline part 41 which consists of the convex parts 40 and 40 is formed. The outer peripheral surface of each convex part 40 which comprises such an incomplete spline part 41 inclines in the direction where an outer diameter dimension becomes small, so that it goes to the other axial direction. Further, one axial end edge of the outer peripheral surface of each convex portion 40, 40 of the incomplete spline portion 41 is continuous with the other axial end edge of the outer peripheral surface of each convex portion 37, 37 constituting the male spline portion 38. doing. On the other hand, the other axial end edge of the outer peripheral surface of each convex portion 40, 40 of the incomplete spline portion 41 is continuous with one axial end edge of the outer peripheral surface of the small diameter shaft portion 33. In the case of this example, the diameter of the circumscribed circle of the concave portions 36, 36 of the male spline portion 38 is equal to the diameter of the circumscribed circle of the concave portions 39, 39 of the incomplete spline portion 41.

  The small-diameter shaft portion 33 is provided from a position adjacent to the other axial side of the continuous portion 32 to a portion closer to the other axial end portion of the inner shaft 9a. Such a small diameter shaft portion 33 includes a large diameter portion 42, a small diameter portion 43, a stepped portion 44, a reference hole 45, and an outward flange portion (caulking portion) 46.

  Of these, the large-diameter portion 42 is formed from one end portion in the axial direction of the small-diameter shaft portion 33 to a portion closer to the other end in the axial direction. The outer peripheral surface of such a large diameter portion 42 is formed in a cylindrical surface shape whose outer diameter does not change in the axial direction.

  The small diameter portion 43 is formed in a portion near the other end of the small diameter shaft portion 33. On the outer peripheral surface of such a small-diameter portion 43, male serrations 47, which are concave and convex portions formed by alternately arranging concave portions and convex portions in the circumferential direction, are formed. The diameter of the circumscribed circle of the convex portion constituting the male serration 47 is smaller than the outer diameter of the large diameter portion 42.

  The step portion 44 is formed in a state where the other axial end edge of the outer peripheral surface of the large diameter portion 42 and the one axial end edge of the outer peripheral surface of the small diameter portion 43 are continuous. Such a stepped portion 44 exists on a virtual plane orthogonal to the central axis of the small diameter shaft portion 33.

  The reference hole 45 is formed in a state in which the other axial end is opened on the other axial end surface of the small diameter shaft portion 33. Further, the position of the rear end edge of the reference hole 45 in the axial direction is located in the axially intermediate portion of the small diameter portion 43. The reference hole 45 is formed by drilling the other axial end surface of the flange-shaped member that is the material of the inner shaft 9a.

  The outward flange 46 is formed at the other axial end of the small-diameter shaft portion 33 so as to protrude radially outward from the outer peripheral surface of the small-diameter portion 43 over the entire circumference. Such an outward flange 46 is formed by, for example, rolling the other end in the axial direction of the intermediate material obtained by forming the reference hole 45 with respect to the material to the entire circumference by rolling caulking.

  The yoke portion 34 is coupled and fixed to the other axial end portion of the small diameter shaft portion 33. In the case of this example, the front side of the universal joints 3c and 3d (see FIG. 5) by the yoke portion 34, the cross shaft 48, and the yoke 49 supported and fixed to the base end portion of the input shaft 6. 3d) on the left side of 3).

Such a yoke portion 34 is provided in a state of extending from the substantially cylindrical base portion 50 and two positions opposite to the central axis of the base portion 50 on the outer peripheral surface of the base portion 50 to the other side in the axial direction. And a pair of arm portions 51, 51.
Of these, the base 50 has a central hole 52 formed at the center. On the inner peripheral surface of the center hole 52, a female serration 53, which is an uneven portion formed by alternately arranging concave portions and convex portions in the circumferential direction, is formed. Such a base 50 is inserted into the center hole 52 through the small-diameter portion 43 and the female serration 53 and the male serration 47 are serrated to engage the stepped portion 44 and the outward flange. It is clamped between the portions 46.

In addition, a pair of circular holes 54 and 54 are formed in the arm portion 51 and 51 near the end on the opposite side to the base 50 in the axial direction so that the central axes are coaxial with each other. Yes.
Further, in the assembled state shown in FIG. 3, bottomed cylindrical bearing cups 55 and 55 are fitted and fixed inside the circular holes 54 and 54 of the both arm portions 51 and 51, respectively. At the same time, a pair of shaft portions 57 of the four shaft portions 57, 57 constituting the cross shaft 48 are provided inside the bearing cups 55, 55 via a plurality of needles 56, 56, respectively. , 57 are rotatably supported.

  Of the four shaft portions 57, 57 constituting the cross shaft 48, a pair of shaft portions 57 other than the shaft portions 57, 57 supported in the circular holes 54, 54 of the yoke portion 34 ( The end of one shaft portion 57 is not shown in the inside of a circular hole (not shown) formed in a pair of arm portions 58 (one arm portion 58 is not shown) constituting the yoke 49, It is rotatably supported via a bearing cup (not shown) and a needle (not shown).

  The slit 35 is formed by cutting the inner shaft 9a. The slit 35 has a cross-sectional shape on a virtual plane including the central axis of the inner shaft 9a, and the axial direction of the inner shaft 9a. It is formed from one end edge to an axially intermediate portion of the spline forming portion 31 (a portion positioned slightly on the other side in the axial direction from the central position of the spline forming portion 31 in the axial direction). In such a slit 35, one end in the axial direction opens at one end surface in the axial direction of the inner shaft 9a, and both ends in the width direction (both ends in the front and back directions in FIG. 3) and both ends in the up and down direction (in FIG. 3). Both ends of the paper in the vertical direction divide a portion from one end edge in the axial direction to the middle portion in the axial direction of the outer peripheral surface of the spline forming portion 31 (the male spline portion 38) into four in the circumferential direction. Further, in the case of this example, the radially outer end portion of the slit 35 is opened only in the concave portion 36 constituting the male spline portion 38 formed in the inner shaft 9a, respectively, and the circumferential side surface of the convex portion 37 is thus formed. There is no opening on the (surface transmitting torque).

In the case of this example, the other axial end edge (back end edge) of the slit 35 is positioned on one axial side than the axial end edge of the continuous portion 32. Specifically, the other axial end edge of the slit 35, the length in the axial direction of the male spline section 38 when the L _38, the axial end edge of the male spline section 38, (0. 5 to 0.9) · L ₃₈ . In the case of this example, portions of the inner shaft 9a other than the slit 35 and the reference hole 45 are formed in a solid shape.

  A coating layer 59 made of a synthetic resin that is slippery (having a low friction coefficient) is provided on the outer peripheral surface of the male spline portion 38 that constitutes the inner shaft 9a. Specifically, in the case of this example, the coating layer 59 is a portion of the outer peripheral surface of the inner shaft 9a that is closer to one end in the axial direction of the small-diameter shaft portion 33 from one end edge in the axial direction of the spline forming portion 31 (see above It is a portion located on the other side in the axial direction from the other end edge in the axial direction of the continuous portion 32, and is provided in a portion extending to a position indicated by a straight line X in FIG.

  In the case of this example, the male spline portion 38 is covered over the entire length including the slit 35 and is covered with the coating layer 59. In other words, the synthetic resin coating layer 59 enters the entire interior of the slit 35 and is filled with the synthetic resin coating layer 59.

  The inner shaft 9a having the above-described configuration has the male spline portion 38 extending over the entire length, and is spline engaged with the female spline portion 22 of the outer tube 10a via the coating layer 59. 10a. In this assembled state, a predetermined amount of tightening allowance is provided at the engaging portion between the male spline portion 38 and the female spline portion 22. In this manner, the inner shaft 9a and the outer tube 10a are combined in a state where torque can be transmitted and the entire length can be expanded and contracted.

According to the intermediate shaft 4a of the present example having the above-described configuration, the rotation direction of the engaging portion between the male spline portion 38 of the inner shaft 9a and the female spline portion 22 of the outer tube 10a is not stable. Even when a structure that can be kept small is adopted, the sliding resistance between the inner shaft 9a and the outer tube 10a can be kept small.
That is, in this example, the slit 35 is formed in the inner shaft 9a, and the inside of the slit 35 is filled with the coating layer 59 made of the synthetic resin. For this reason, the radial rigidity of the portion in which the slit 35 is formed in the portion in which the male spline portion 38 is formed can be appropriately reduced. Therefore, in order to prevent rattling in the rotational direction of the engaging portion between the male spline portion 38 and the female spline portion 22, even when the engaging portion is provided with a tightening allowance, the sliding with respect to the tightening allowance is prevented. Variations in dynamic resistance (sliding load) can be made insensitive, and sliding of the inner shaft 9a with respect to the outer tube 10a can be stabilized.
By providing an air region covered with the coating layer 59 inside the slit 35, a damper effect can be provided, and the radial rigidity of the portion where the slit 35 is formed can be appropriately adjusted.

  Further, since the radial rigidity of the male spline portion 38 can be appropriately reduced as described above, the rotation direction of the engaging portion between the male spline portion 38 and the female spline portion 22 is not stable. In order to prevent this, even when a structure in which a tightening margin is provided at the engaging portion is employed, the sliding resistance (sliding load) with respect to the tightening margin can be reduced. Further, the fluctuation of the sliding resistance (sliding load) becomes insensitive, and the sliding of the inner shaft 9a with respect to the outer tube 10a can be stabilized. Furthermore, even when a large range (dimensional tolerance) in which the error of the inner shaft 9a can be tolerated is ensured, it is possible to prevent the sliding resistance from increasing due to the influence of the dimensional tolerance. Therefore, the manufacturing cost of the inner shaft 9a and the outer tube 10a can be reduced.

  In the case of this example, the other end edge in the axial direction of the slit 35 is arranged on one side in the axial direction than the other end edge in the axial direction of the male spline portion 38. For this reason, it is possible to secure the rigidity of a portion where stress is easily concentrated, such as a boundary portion between the continuous portion 32 and the small diameter shaft portion 33 in the inner shaft 9a. As a result, the durability of the inner shaft 9a can be improved.

  In the above-described embodiment, the present invention has been described with respect to an example in which the present invention is applied to an inner shaft among intermediate shafts constituting a steering device. However, the present invention can be applied to the structure of a telescopic shaft used for various purposes other than such an inner shaft.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3a, 3b, 3c, 3d Universal joint 4, 4a Intermediate shaft 5 Steering gear unit 6 Input shaft 7 Tie rod
8 Male spline part 9, 9a, Inner shaft
10, 10a Outer tube 11 First yoke 12 Female spline portion 13 Second yoke 14 Cross shaft 15 Yoke 16 Cross shaft 17 Yoke 18 Small diameter cylindrical portion 19 Continuous portion 20 Large diameter cylindrical portion 21 Yoke portion 22 Female spline portion 23 Arm Part 24 circular hole 25 bearing cup 26 needle 27 cross shaft 28 shaft part 29 yoke 30 arm part 31 spline forming part 32 continuous part 33 small diameter shaft part 34 yoke part 35 slit 36 concave part 37 convex part 38 male spline part 39 concave part 40 convex part 41 Incomplete spline part 42 Large diameter part 43 Small diameter part 44 Step part 45 Reference hole 46 Outward flange part 47 Male serration 48 Cross shaft 49 Yoke 50 Base part 51 Arm part 52 Center hole 53 Female serration 54 Circular hole 55 Bearing cup 56 Needle 57 Shaft part 58 Arm part 59 Coating layer

Claims (1)

A male shaft having a male spline portion formed on the outer peripheral surface of one axial end portion;
A coating layer provided in a state of covering the outer peripheral surface of the male spline part;
A female shaft having a female spline portion formed on the inner peripheral surface,
By engaging the male spline part and the female spline part through the coating layer, the male shaft and the female shaft are combined in a state where torque can be transmitted and the total length can be expanded and contracted. A telescopic shaft,
The male shaft has an outer peripheral surface at one end portion in the axial direction of the male shaft, and a cross-shaped slit opening in one end surface in the axial direction of the male shaft,
The slit is covered with the coating layer,
Telescopic shaft.

Images